A method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range and a new energy vehicle battery case

Abstract

The present invention discloses a method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range, and a new energy vehicle battery case, comprising: preparing polyamide aerogel using polyamide fiber, or preparing polyamide aerogel using a thermoplastic resin raw material by 3D printing; dispersing a conductive filler and a flame retardant in a thermoplastic resin powder and stirring the mixture to uniformly disperse the conductive filler and the flame retardant; hot-pressing the obtained mixed powder with a carbon fiber unidirectional tape to obtain a carbon fiber reinforced tape material; laminating and hot-pressing the carbon fiber reinforced tape material to obtain a carbon fiber composite material sheet; using the polyamide aerogel as an intermediate layer and the carbon fiber composite material sheet as an outer layer to form a sandwich structure composite material. The present invention can be applied to the structure and materials of new energy vehicle battery cases, and overall has good mechanical strength, heat dissipation and heat insulation properties, flame retardancy, and electromagnetic shielding properties.

Description

Technical Field

[0001] The present invention relates to a method for preparing a composite material for a new energy vehicle battery case and a new energy vehicle battery case, and in particular to a method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range and a new energy vehicle battery case. Background Art

[0002] Environmental protection is a major theme today, and green environmental protection is the primary path to modernization. The automotive industry is a key pillar of the national economy, playing a vital role in national economic and social development. The new energy vehicle industry is a strategic emerging industry, and the development of energy-efficient vehicles is an effective measure to promote energy conservation and emission reduction.

[0003] As the power source of electric vehicles, the quality of batteries not only affects the vehicle's range, but also its operating environment, safety, and reliability. It can be said that the development of power batteries determines the future of pure electric vehicles. The characteristics of power batteries are significantly affected by ambient temperature, and the optimal operating temperature for power batteries is generally between 0-40°C. Because the electrolytes within new energy vehicle batteries are composed of flammable and volatile non-aqueous solutions, they easily evaporate and produce gases at high temperatures. Excessive battery temperatures not only affect battery activity but also shorten its lifespan. In low-temperature environments, the available energy and power decrease significantly. Long-term use in low-temperature environments accelerates the aging of power batteries, shortening their service life. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range and a new energy vehicle battery case. The first technical problem to be solved is to fully consider the battery's operating temperature range, weight, strength, performance and service life when designing the battery shell. The second is to provide an electromagnetic shielding function for the battery case to prevent interference with the normal operation of the vehicle-mounted equipment and the physical and mental health of the people in the car. The last technical problem to be solved is to provide a composite material for a new energy vehicle battery case suitable for a wide temperature range. The molded products and new energy vehicle battery cases using the composite material have excellent comprehensive performance. While meeting the daily use requirements of the battery case, they enhance the functions such as lightweight, thermal stability, and electromagnetic shielding.

[0005] In summary, the technical problems to be solved by the present invention include but are not limited to the defects of the existing technology such as narrow ambient temperature range of new energy vehicle batteries, large box mass, poor flame retardancy, electromagnetic interference, etc.

[0006] The present invention provides the following solutions:

[0007] A method for preparing a composite material for a new energy vehicle battery box suitable for a wide temperature range, comprising the following steps:

[0008] Step 1: Select polyamide fiber as the main precursor to construct the three-dimensional network of aerogel:

[0009] Polyamide nanofibers and polyamide chopped fibers (micrometer-sized segments) are placed in a dispersion, and the mixture is then rotated at high speed in a homogenizer for a period of time to obtain a uniform polyamide fiber suspension. The polyamide fiber suspension is freeze-dried, and the freeze-dried polyamide three-dimensional fiber skeleton is structurally reinforced by heat welding to obtain a polyamide aerogel, or:

[0010] Polyamide aerogel was produced by 3D printing using PA66 pellets as raw materials;

[0011] Step 2: preparing a carbon fiber reinforced tape material: dispersing a conductive filler and a flame retardant in a thermoplastic resin powder and uniformly dispersing the powder using a mechanical stirrer, evenly spreading the obtained mixed powder on a carbon fiber unidirectional tape, and hot pressing the obtained carbon fiber reinforced tape material;

[0012] Step 3: Preparation of external materials: Lay the carbon fiber reinforced tape material obtained in step 2 in layers at 0° / 90° / 45° / -45° / 90° / 0°, and hot press after laying to obtain a carbon fiber composite material plate;

[0013] Step 4: Use the polyamide aerogel prepared in step 1 as the interlayer and the carbon fiber composite material plate as the outer layer, and hot-press to obtain a composite material with a sandwich structure suitable for new energy vehicle battery boxes in a wide temperature range. When using, heat carrier oil needs to be added to the interlayer according to the specific environment.

[0014] Furthermore, in the step one, the polyamide nanofiber is PA6 nanofiber or aromatic polyamide nanofiber (aramid 1313 or aramid 1414) made by electrospinning, wherein the content of polyamide nanofiber is 10-20wt%; the polyamide chopped fiber is PA66 chopped fiber, the fiber segment length is 3-8mm, wherein the content of PA66 fiber is 80-90wt%; the dispersion is a mixture of water and tert-butanol, wherein the volume ratio of water to tert-butanol is 3-4:1; the speed of the homogenizer is 10000-20000 rpm, and the dispersion time is 20-30 minutes; the diameter of the 3D printed fiber filament is 50 microns to 400 microns; and the thickness of the obtained polyamide aerogel is 3mm.

[0015] Furthermore, in the step 2, the thermoplastic resin is one or more of polyamide (PA6, PA66), polypropylene, polyurethane, polyimide or polyetheretherketone, and the resin content is 30wt%-40wt%; the conductive filler is one or more of multi-walled carbon nanotubes with carboxyl groups and MXene, wherein the length of the multi-walled carbon nanotubes with carboxyl groups is 1.0-2.0 microns and the aspect ratio is 1:8, wherein the content of the conductive filler accounts for 1wt%-3wt% of the overall powder mixture; the flame retardant is a phosphorus-halogen system flame retardant, generally phosphorus pentabromide, wherein the content of the flame retardant accounts for 5wt%-6wt% of the overall powder mixture, and the carbon fiber selected for the carbon fiber reinforced tape material is T600 or T800, and the thickness of the carbon fiber reinforced tape material is 0.5mm.

[0016] Furthermore, in step 3, the specific temperature of the hot pressing is the processing temperature of the selected resin, and the pressure is 10-15 MPa;

[0017] In step 4, the heat transfer oil is also called heat transfer oil, and the heat transfer oil is alkyl biphenyl type heat transfer oil; the sealing material for the liquid is fluororubber; in summer, when the ambient temperature is high, the heat transfer oil is added; in winter, when the ambient temperature is low, the heat transfer oil is discharged;

[0018] In step 4, for the northern region, the ambient temperature is particularly low in winter, so there is no need to add heat transfer oil to the aerogel; when the ambient temperature is high in summer, heat carrier oil needs to be injected into the aerogel; for the southern region, the ambient temperature is very high in summer and not very low in winter, and the material injected with heat carrier oil can be used directly (whether the heat carrier oil needs to be removed depends on the temperature change).

[0019] A method for preparing a composite material, comprising:

[0020] Preparation of polyamide aerogel using polyamide fibers, and / or: Preparation of polyamide aerogel using thermoplastic resin raw materials by 3D printing;

[0021] The conductive filler and the flame retardant are dispersed in the thermoplastic resin powder and stirred to make them uniformly dispersed, and the obtained mixed powder and the carbon fiber unidirectional tape are hot pressed to obtain a carbon fiber reinforced tape material;

[0022] Laminating and hot-pressing the carbon fiber reinforced tape material to obtain a carbon fiber composite material plate;

[0023] The polyamide aerogel is used as the middle layer and the carbon fiber composite material plate is used as the outer layer to form a composite material with a sandwich structure.

[0024] Furthermore, the polyamide fiber is PA6 nanofiber or aromatic polyamide nanofiber produced by electrospinning;

[0025] During the preparation of the mixed powder, a dispersion liquid is added, wherein the dispersion liquid is a mixture of water and tert-butyl alcohol, and a homogenizer is used to evenly disperse the mixed powder during the uniform dispersion process;

[0026] The polyamide aerogel is prepared by 3D printing using thermoplastic resin raw materials. Specifically, the diameter of the 3D printed fiber filament is 50 microns to 400 microns, and the thickness of the obtained polyamide aerogel is 3 mm.

[0027] The thermoplastic resin is one or more of polyamide, polypropylene, polyurethane, polyimide or polyetheretherketone;

[0028] The conductive filler is one or more of multi-walled carbon nanotubes and MXene with carboxyl groups, and the flame retardant is a phosphorus-halogen system flame retardant.

[0029] Furthermore, the carbon fiber selected for the carbon fiber reinforced tape material is T600 or T800, and the thickness of the carbon fiber reinforced tape material is 0.5 mm;

[0030] During the hot pressing process of the mixed powder and the carbon fiber unidirectional tape, the specific temperature of the hot pressing is the resin processing temperature, and the pressure is 10-15 MPa.

[0031] A composite material for a new energy vehicle battery box, wherein the composite material is prepared by the method described.

[0032] A composite material molded product for a new energy vehicle battery case, which is applied to a new energy vehicle battery case within a wide temperature range. The composite material molded product for a new energy vehicle battery case includes a composite material for a new energy vehicle battery case, which is prepared using the method described.

[0033] A new energy vehicle battery case includes a composite material molded product for a new energy vehicle battery case.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. The composite material for new energy vehicle battery cases suitable for a wide temperature range and its preparation method of the present invention achieve the goals of wide temperature range use, high-temperature heat dissipation, and low-temperature thermal insulation by using polyamide aerogel as an interlayer. Aerogel is a Class A fireproof and thermal insulation material with excellent thermal insulation performance. It is lightweight and has a low thermal conductivity coefficient. The use of polyamide as the main raw material not only gives the aerogel flexibility and toughness, strong thermal insulation properties, high fire resistance, and excellent mechanical properties, but also gives it the additional characteristics of long service life and strong oil resistance. Strong oil resistance also makes it possible to introduce heat carrier oil into the subsequent system.

[0036] 2. The sandwich structure material prepared by the composite material for the battery box of new energy vehicles with a wide temperature range and the preparation method thereof of the present invention is suitable for the northern region where the ambient temperature is particularly low in winter. It is not necessary to add heat transfer oil into the aerogel. In this way, the material can better maintain the temperature inside the battery, and the temperature generated when the battery is working will also be retained, which can greatly increase the battery life and reduce the rapid drop in battery power and shutdown caused by sudden temperature drops. For the summer when the ambient temperature is high, it is necessary to inject heat carrier oil into the aerogel. After the heat carrier oil is injected, the "infinite path" effect and "zero-to-zero" effect of the aerogel are broken. The "flow" effect is beneficial to the transmission of heat, and heat transfer oil is a special oil with good thermal stability for indirect heat transfer. It has the performance of resisting thermal cracking and chemical oxidation, good heat transfer efficiency, fast heat dissipation, good thermal stability and long service life. The alkyl biphenyl type heat transfer oil used in this patent has a boiling point of >330℃ and is an ideal product for use in the range of 300-340℃. It is safe while ensuring heat transfer. For the southern region, the ambient temperature is very high in summer and not very low in winter, so the material injected with heat carrier oil can be used directly (whether the heat carrier oil needs to be removed depends on the temperature change).

[0037] 3. The sandwich structure material produced by the composite material for new energy vehicle battery cases suitable for a wide temperature range and its preparation method, due to its structural characteristics and the types of materials selected, also possesses electromagnetic shielding, sound absorption, and fire retardant properties. The introduction of carbon nanotubes and carbon fibers into the carbon fiber composite material creates a three-dimensional electromagnetic shielding network focused on absorption, reducing secondary air pollution. The sandwich structure itself facilitates electromagnetic wave absorption, which improves the material's electromagnetic shielding effectiveness. The presence of polyamide aerogel within the composite material also provides sound absorption and fire retardant properties.

[0038] 4. The composite material for new energy vehicle battery box suitable for a wide temperature range of the present invention has good mechanical strength, heat dissipation and heat insulation performance, flame retardancy and electromagnetic shielding performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a flow chart of a method for preparing composite materials for new energy vehicle battery cases suitable for a wide temperature range.

[0041] Figure 2 It is a schematic diagram of the composite material structure with a fluororubber stopper.

[0042] Figure 3 This is a schematic diagram of the structure of a composite material without a fluororubber plug (direct injection of heat carrier oil).

[0043] Figure 4 This is a rendering of a composite material structure with a fluororubber stopper.

[0044] Figure 5 This is a structural rendering of a composite material without a fluororubber plug (direct injection of heat carrier oil). DETAILED DESCRIPTION

[0045] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0046] The power battery directly determines a vehicle's range and the ambient temperature in which it can operate. As a direct protective device for the battery, the battery casing's design must fully consider its operating temperature range, weight, strength, safety, and service life. Furthermore, its high-intensity operation can generate electromagnetic interference, which can not only affect the normal operation of the equipment but, in the long term, even impact the physical and mental health of the driver and even passengers. Therefore, electromagnetic shielding must be considered in the design process. This article examines the material selection and design of new energy vehicle battery casings, analyzing research priorities and development directions.

[0047] The advancement of science and technology in society places higher demands on materials, requiring them to possess excellent comprehensive performance. While meeting daily requirements, battery casings for new energy vehicles also place higher demands on lightweighting, thermal stability, and electromagnetic shielding. Therefore, developing lightweight, stable materials with electromagnetic shielding properties remains a key research and development priority.

[0048] Example 1: This example discloses a method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range in a specific application scenario, specifically the following steps:

[0049] Step 1: 20 wt% of electrospun polyamide nanofibers (PA6) and 80 wt% of polyamide chopped fibers (PA66, micrometer size, 5 mm) were placed in a dispersion of water and tert-butanol (water / tert-butanol v / v = 3:1). The mixture was then spun in a homogenizer at 20,000 rpm for 30 minutes to produce a uniform polyamide fiber suspension. The polyamide fiber suspension was freeze-dried, and the freeze-dried polyamide three-dimensional fiber skeleton was structurally reinforced by heat welding to produce a polyamide aerogel.

[0050] Step 2: Disperse 1wt% of multi-walled carbon nanotubes with carboxyl groups and 6wt% of phosphorus pentabromide in 40wt% of polyamide (PA66) powder and disperse them evenly using mechanical stirring. Spread the obtained mixed powder evenly on the carbon fiber unidirectional tape (T800), and obtain a carbon fiber reinforced tape material with a thickness of 0.5mm after hot pressing.

[0051] Step 3: Preparation of external materials: The carbon fiber reinforced tape material obtained in step 2 is layered at 0° / 90° / 45° / -45° / 90° / 0°, and hot pressed after layering to obtain a carbon fiber composite material plate.

[0052] Step 4: Use the 3 mm thick polyamide aerogel prepared in step 1 as the interlayer and the carbon fiber composite material sheet as the outer layer, and hot press to obtain a composite material with a sandwich structure suitable for new energy vehicle battery box with a wide temperature range. When using, heat carrier oil (alkyl biphenyl type heat transfer oil) needs to be added to the interlayer in combination with a specific environment.

[0053] This implementation can be combined with any one or more embodiments of the present application specification to form more embodiments, as long as there is no technical conflict or contradiction. Due to space limitations, they will not be described in detail.

[0054] Example 2:

[0055] This embodiment is basically the same as Example 1, except that in step 1, 20wt% of aromatic polyamide nanofibers (aramid 1313) and 80wt% of polyamide short fibers (PA66, micron scale, 8mm) are placed in a dispersion prepared from water and tert-butyl alcohol, wherein (water / tert-butyl alcohol v / v=4:1), and the mixture is then rotated at a high speed of 10,000 rpm for 20 minutes in a homogenizer to obtain a uniform polyamide fiber suspension. The polyamide fiber suspension is freeze-dried, and the freeze-dried polyamide three-dimensional fiber skeleton is structurally enhanced by heat welding to obtain a polyamide aerogel. This embodiment can also be combined with any embodiment of the present application specification to form more embodiments, as long as there is no technical conflict or contradiction, which will not be repeated due to space limitations.

[0056] Example 3:

[0057] This embodiment is basically the same as Example 1, except that in step 1, 10 wt% of aromatic polyamide nanofiber (aramid 1414) and 90 wt% of polyamide chopped fiber (PA66, micron scale, 3 mm) segments are selected. This embodiment can also be combined with any one or more embodiments of the present application specification to form more embodiments, as long as there is no technical conflict or contradiction. Due to space limitations, they will not be elaborated on.

[0058] Example 4: This example is essentially the same as Example 1, except that in step 1, PA66 pellets are used as the raw material to produce polyamide aerosols via 3D printing. The diameter of the 3D printed fiber filaments is 50 microns. This example can also be combined with any one or more of the examples in this specification to form further examples, as long as there are no technical conflicts or contradictions. Due to space limitations, this will not be further elaborated.

[0059] Example 5: This example is essentially the same as Example 1, except that in step 1, PA66 pellets are used as the raw material to produce polyamide aerosols via 3D printing. The diameter of the 3D printed fiber filaments is 400 microns. This example can also be combined with any one or more examples in this specification to form further examples, as long as there are no technical conflicts or contradictions. Due to space limitations, this will not be further elaborated.

[0060] Example 6: This example is essentially the same as Example 1, except that in step 2, 3 wt% of multi-walled carbon nanotubes with carboxyl groups and 5 wt% of phosphorus pentabromide are dispersed in 30 wt% of polyimide powder and uniformly dispersed using mechanical stirring. The resulting mixed powder is evenly spread on a carbon fiber unidirectional tape (T600), and hot pressed to produce a carbon fiber reinforced tape material with a thickness of 0.5 mm. This example can also be combined with any one or more examples in this specification to form further examples, as long as there are no technical conflicts or contradictions. Due to space limitations, this will not be further elaborated.

[0061] Embodiment seven:

[0062] This embodiment is substantially the same as the first embodiment, except that in step 2, 3 wt% of multi-walled carbon nanotubes with carboxyl groups and 6 wt% of phosphorus pentabromide are dispersed in 30 wt% of polypropylene powder and uniformly dispersed using mechanical stirring. The resulting mixed powder is then evenly spread over a carbon fiber unidirectional tape (T600) and hot-pressed to produce a carbon fiber reinforced tape material with a thickness of 0.5 mm. This embodiment can also be combined with any one or more embodiments of this specification to form further embodiments, as long as there are no technical conflicts or contradictions. Due to space limitations, this will not be further elaborated.

[0063] The performance of the composite materials for new energy vehicle battery cases suitable for a wide temperature range, prepared in Examples 1-7, was tested. The test results are shown in the following table.

[0064] Performance of composite materials for new energy vehicle battery cases suitable for a wide temperature range prepared in Examples 1-7

[0065]

[0066] Example 8: This example discloses a method for preparing a composite material, the method steps specifically including:

[0067] Step 1: preparing polyamide aerogel using polyamide fiber, and / or: preparing polyamide aerogel using thermoplastic resin raw material by 3D printing;

[0068] Specifically, the polyamide fiber is PA 6 nanofiber or aromatic polyamide nanofiber produced by electrospinning;

[0069] Exemplarily, the aromatic polyamide nanofiber is aramid 1313 or aramid 1414, wherein the content of polyamide fiber is 10-20 wt%; the polyamide chopped fiber is PA66 chopped fiber, the fiber segment length is 3-8 mm, wherein the content of PA66 fiber is 80-90 wt%.

[0070] The diameter of the 3D printed fiber filaments ranged from 50 microns to 400 microns, and the thickness of the resulting polyamide aerogel was 3 mm.

[0071] Specifically, the thermoplastic resin is one or more of polyamide (PA6, PA66), polypropylene, polyurethane, polyimide or polyetheretherketone.

[0072] Illustratively, in this embodiment, the resin content is 30 wt%-40 wt%.

[0073] Step 2: Dispersing the conductive filler and the flame retardant in the thermoplastic resin powder and stirring them to make them uniformly dispersed, and hot-pressing the obtained mixed powder with the carbon fiber unidirectional tape to obtain a carbon fiber reinforced tape material;

[0074] Glossary: ​​Carbon fiber unidirectional tape is a type of carbon fiber composite material, and carbon fiber is essentially a stranded material. It is a lightweight and extremely durable material. Carbon fiber composites have approximately 60% of the strength and stiffness of steel (with a density of 20%) and approximately 1.7 times the strength and stiffness of aluminum (with a density of 56%), making them an excellent manufacturing material for many components. Engineers and designers choose carbon fiber composites for demanding applications because of their high stiffness and weight strength, and because they allow physical properties to be customized in specific locations and directions within the part.

[0075] Carbon fiber composites are made by combining carbon fibers with epoxy resin or other materials. How they are manufactured depends largely on the desired properties and intended use. They can be manufactured as unidirectional, bidirectional, or quasi-isotropic materials and in various shapes and sizes as needed. Manufacturing processes for carbon fiber composites include filament winding, pultrusion, tooling, resin transfer, and autoclave processing. Carbon fiber composites offer a variety of advantages. One benefit is that they are more durable than other materials. Other benefits of carbon fiber include high tensile strength, high stiffness to weight, low thermal expansion, high chemical resistance, and X-ray translucency.

[0076] Specifically, the conductive filler and the flame retardant are dispersed in the thermoplastic resin powder and uniformly dispersed by mechanical stirring, the obtained mixed powder is evenly spread on the carbon fiber unidirectional tape, and then subjected to a hot pressing process.

[0077] Specifically, a dispersion liquid is added during the preparation of the mixed powder, and the dispersion liquid is a mixture of water and tert-butanol.

[0078] Exemplarily, the volume ratio of the water and tert-butanol mixture is (3-4):1;

[0079] Specifically, a homogenizer is used to disperse the mixed powder uniformly;

[0080] Exemplarily, the rotation speed of the homogenizer is 10,000-20,000 rpm, and the dispersion time is 20-30 minutes.

[0081] Specifically, the conductive filler is one or more of multi-walled carbon nanotubes and MXene with carboxyl groups, and the flame retardant is a phosphorus-halogen system flame retardant;

[0082] For example, the multi-walled carbon nanotubes with carboxyl groups have a length of 1.0-2.0 microns and an aspect ratio of 1:8, wherein the conductive filler accounts for 1 wt%-3 wt% of the entire powder mixture;

[0083] For example, the flame retardant is generally phosphorus pentabromide, wherein the content of the flame retardant accounts for 5wt%-6wt% of the entire powder mixture.

[0084] Step 3, performing layering and hot pressing on the carbon fiber reinforced tape material to obtain a carbon fiber composite material plate;

[0085] Specifically, during the hot pressing of the mixed powder and the carbon fiber unidirectional tape, the specific temperature of the hot pressing is the resin processing temperature;

[0086] Exemplarily, the pressure during the hot pressing treatment is 10-15 MPa.

[0087] Specifically, the carbon fiber used in the carbon fiber reinforced tape material is T600 or T800, and the thickness of the carbon fiber reinforced tape material is 0.5 mm;

[0088] Step 4: Use the polyamide aerogel as the middle layer and the carbon fiber composite material plate as the outer layer to form a composite material with a sandwich structure.

[0089] For composite materials with prepared sandwich structures, heat carrier oil needs to be added to the interlayer in combination with a specific environment when used in specific application scenarios.

[0090] For the method steps disclosed in the above embodiments, for the purpose of simple description, the method steps are expressed as a series of action combinations. However, those skilled in the art should be aware that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

[0091] Example 9: This example discloses a composite material for a new energy vehicle battery case, and the composite material is prepared using the preparation method disclosed in any example of this application.

[0092] Example 10: This example discloses a composite material molded product for a new energy vehicle battery case. The composite material molded product for a new energy vehicle battery case is applied to a new energy vehicle battery case within a wide temperature range. The composite material molded product for a new energy vehicle battery case includes the composite material disclosed in Example 9. The composite material disclosed in Example 9 is prepared using the preparation method disclosed in any example of this application.

[0093] Example 11: This example discloses a new energy vehicle battery case, which includes the composite material molded product for the new energy vehicle battery case disclosed in Example 10.

[0094] Example 12: Figures 2 to 5 As shown, first look at the description of the reference numerals: carbon fiber composite sheet 1, three-dimensional skeleton 2, fluororubber plug 3, pore filling 4 (heat carrier oil). The composite layer structure of the new energy vehicle battery fir composite material of this embodiment is: a material with a fluororubber plug (heat carrier oil can be injected at any time), or a material without a fluororubber plug (heat carrier oil can be directly injected). This embodiment can be combined with any embodiment in the specification of this application to form more embodiments, for example, it can be combined with the embodiment involving the preparation method to obtain a product prepared by the preparation method, for example, it can be combined with the embodiment involving composite materials to apply the composite materials to the composite layer structure, for example, it can be combined with the embodiment involving molded products to be suitable for more different application scenarios. As long as there is no conflict or contradiction in the technical principles and technical common sense, this embodiment can be combined with other embodiments of the specification of this application to form an infinite number of embodiments.

[0095] Example 13: Figure 1 As shown, this embodiment also provides a composite material for a new energy vehicle battery case suitable for a wide temperature range and a preparation method thereof, the steps are as follows:

[0096] Step 1 (S1): Polyamide fibers are selected as the primary precursor to construct the three-dimensional aerogel network. Method 1: Polyamide nanofibers and polyamide chopped fibers (micrometer-sized) are placed in a dispersion solution, and the mixture is then rotated at high speed in a homogenizer for a period of time to produce a uniform polyamide fiber suspension. The polyamide fiber suspension is freeze-dried, and the freeze-dried polyamide three-dimensional fiber skeleton is structurally reinforced using heat welding to produce a polyamide aerogel. Method 2: Polyamide aerogel is produced using PA66 pellets as raw material using 3D printing.

[0097] Step 2 S2, preparing carbon fiber reinforced tape material: conductive filler and flame retardant are dispersed in thermoplastic resin powder and dispersed evenly by mechanical stirring, the obtained mixed powder is evenly spread on the carbon fiber unidirectional tape, and the carbon fiber reinforced tape material is obtained by hot pressing.

[0098] Step 3 S3, preparation of external materials: the carbon fiber reinforced tape material obtained in step 2 is layered at 0° / 90° / 45° / -45° / 90° / 0°, and hot pressed after layering to obtain a carbon fiber composite material plate.

[0099] Step 4 S4: The polyamide aerogel prepared in step 1 is used as an interlayer and the carbon fiber composite material plate is used as an outer layer. A composite material having a sandwich structure suitable for a new energy vehicle battery box within a wide temperature range is obtained by hot pressing. When used, heat carrier oil needs to be added to the interlayer in combination with a specific environment.

[0100] Preferably, in step 1, the polyamide nanofibers are PA 6 nanofibers or aromatic polyamide nanofibers (aramid 1313 or aramid 1414) produced by electrospinning, wherein the content of the polyamide nanofibers is 10-20 wt%.

[0101] Preferably, in step 1, the polyamide chopped fibers are PA66 chopped fibers, the fiber segment length is 3-8 mm, and the content of the PA66 fibers is 80-90 wt%.

[0102] Preferably, in step 1, the dispersion liquid is a mixture of water and tert-butanol, wherein (water / tert-butanol v / v=3-4:1).

[0103] Preferably, in step 1, the speed of the homogenizer is 10,000-20,000 rpm, and the dispersion time is 20-30 minutes.

[0104] Preferably, in step 1, the diameter of the 3D printing fiber filament is 50 microns to 400 microns.

[0105] Preferably, in step 1, the thickness of the polyamide aerogel obtained is 3 mm.

[0106] Preferably, in step 2, the thermoplastic resin is one or more of polyamide (PA6, PA66), polypropylene, polyurethane, polyimide or polyetheretherketone, and the resin content is 30wt%-40wt%.

[0107] Preferably, in step 2, the conductive filler is one or more of multi-walled carbon nanotubes with carboxyl groups and MXene, wherein the multi-walled carbon nanotubes with carboxyl groups have a length of 1.0-2.0 microns and an aspect ratio of 1:8, and the content of the conductive filler accounts for 1wt%-3wt% of the entire powder mixture.

[0108] Glossary: ​​MXene, discovered at Drexel University in 2011, has a unique combination of properties. It can be made into highly conductive and strong films in layers of only a few atoms, similar to graphene. This new two-dimensional material has very high strength on a plane when it is pulled, and has good conductivity and heat resistance. Unlike graphene's single atoms (carbon), MXene's 2D layer structure can have a wide range of compositions, where M represents an early transition metal, such as titanium or chromium, and X represents carbon and / or nitrogen. Because these compounds are not just a single element, they can be used to functionalize surface layers for different applications. Researchers estimate that there are more than one million MXene alloy compounds that have not yet been discovered.

[0109] Preferably, in step 2, the flame retardant is a phosphorus-halogen system flame retardant, generally phosphorus pentabromide, wherein the content of the flame retardant accounts for 5wt%-6wt% of the entire powder mixture.

[0110] Preferably, in step 2, the carbon fiber selected for the carbon fiber reinforced tape material is T600 or T800, and the thickness of the carbon fiber reinforced tape material is 0.5 mm.

[0111] Preferably, in step 3, the specific temperature of hot pressing is the processing temperature of the selected resin, and the pressure is 10-15 MPa.

[0112] Preferably, in step 4, the heat carrier oil is also called heat transfer oil, and the heat transfer oil is an alkyl biphenyl type heat transfer oil.

[0113] Preferably, in step 4, heat transfer oil is added in summer when the ambient temperature is high; heat transfer oil is discharged in winter when the ambient temperature is low;

[0114] Preferably, in step 4, the sealing material for draining the liquid is fluororubber.

[0115] As long as there is no conflict or contradiction in technical principles and technical common sense, this embodiment can be combined with other embodiments in this application specification to form an infinite number of embodiments.

[0116] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with those in the context of the prior art and, unless specifically defined, will not be interpreted in an idealized or overly formal sense.

[0117] It should be noted that certain terms are used in this specification and claims to refer to specific components. Those skilled in the art will understand that different manufacturers may use different terms to refer to the same component. This specification and claims do not distinguish components based on differences in terms, but rather on differences in their functions.

[0118] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features that are included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the present invention and to form different embodiments. For example, any one of the embodiments claimed in the claims may be used in any combination in the embodiments of the present invention.

[0120] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0121] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0122] All features disclosed in this specification, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, may be combined in any manner. Any feature disclosed in this specification, unless otherwise stated, may be replaced by an alternative feature that is equivalent or serves a similar purpose. That is, unless otherwise stated, each feature is merely an example of a set of equivalent or similar features. Throughout this specification, like reference numerals indicate like elements.

[0123] Those skilled in the art will appreciate that the modules in the devices in the embodiments can be adaptively changed and set in one or more devices different from the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and in addition they can be divided into multiple submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including corresponding claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner can be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including corresponding claims, abstracts and drawings) can be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0124] The words "include" or "comprising" mentioned in the specification and claims are open-ended terms, so they should be understood as "including but not limited to". The preferred embodiments of the present invention will be described later, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be based on the definition of the claims attached thereto. It should be emphasized that the term "include / comprising" when used in the embodiments of the present invention refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components. Terms or subscripts involving ordinal numbers such as "one", "two", "1", "2", "n", "n-" do not necessarily indicate the order of implementation or the degree of importance of the features, elements, steps or components defined by these terms, but are only used to identify between these features, elements, steps or components for the sake of clarity of description.

[0125] In this application, the word "exemplary" is used to mean "serving as an example, illustration, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is given to enable any person skilled in the art to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that one of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other instances, well-known structures and processes are not elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite material for a new energy vehicle battery box suitable for a wide temperature range, characterized in that: Here are the steps: Step 1: Select polyamide fiber as the main precursor to construct the three-dimensional network of aerogel: Polyamide nanofibers and polyamide chopped fibers are placed in a dispersion solution, and the mixture is then rotated at high speed in a homogenizer for a period of time to obtain a uniform polyamide fiber suspension. The polyamide fiber suspension is freeze-dried, and the freeze-dried polyamide three-dimensional fiber skeleton is structurally reinforced by heat welding to obtain a polyamide aerogel, or: Polyamide aerogel was produced by 3D printing using PA66 pellets as raw materials; Step 2: preparing a carbon fiber reinforced tape material: dispersing a conductive filler and a flame retardant in a thermoplastic resin powder and uniformly dispersing the powder using a mechanical stirrer, evenly spreading the obtained mixed powder on a carbon fiber unidirectional tape, and hot pressing the obtained carbon fiber reinforced tape material; Step 3: Preparation of external materials: Laying the carbon fiber reinforced tape material obtained in step 2, and hot pressing the laminated material to obtain a carbon fiber composite material plate; Step 4: Use the polyamide aerogel prepared in step 1 as the interlayer and the carbon fiber composite material plate as the outer layer, and hot-press to obtain a composite material with a sandwich structure suitable for new energy vehicle battery boxes in a wide temperature range. When using, heat carrier oil needs to be added to the interlayer according to the specific environment.

2. The method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range according to claim 1, characterized in that: In the step 1, the polyamide nanofiber is PA 6 nanofiber or aromatic polyamide nanofiber produced by electrospinning, wherein the content of the polyamide nanofiber is 10-20wt%; the polyamide chopped fiber is PA66 chopped fiber, the fiber segment length is 3-8mm, wherein the content of the PA66 fiber is 80-90wt%; the dispersion liquid is a mixture of water and tert-butanol, wherein the volume ratio of water to tert-butanol is 3-4:1; the speed of the homogenizer is 10,000-20,000 rpm, and the dispersion time is 20-30 minutes; the diameter of the 3D printed fiber filament is 50 microns to 400 microns; and the thickness of the obtained polyamide aerogel is 3 mm.

3. The method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range according to claim 1, characterized in that: In the step 2, the thermoplastic resin is one or more of polyamide, polypropylene, polyurethane, polyimide or polyetheretherketone, and the resin content is 30wt%-40wt%; the conductive filler is one or more of multi-walled carbon nanotubes with carboxyl groups and MXene, wherein the length of the multi-walled carbon nanotubes with carboxyl groups is 1.0-2.0 microns and the aspect ratio is 1:8, wherein the content of the conductive filler accounts for 1wt%-3wt% of the overall powder mixture; the flame retardant is a phosphorus-halogen system flame retardant, wherein the content of the flame retardant accounts for 5wt%-6wt% of the overall powder mixture, and the carbon fiber selected for the carbon fiber reinforced tape material is T600 or T800, and the thickness of the carbon fiber reinforced tape material is 0.5 mm.

4. The method for preparing a composite material for a new energy vehicle battery case suitable for a wide temperature range according to claim 1, characterized in that: In step 3, the specific temperature of hot pressing is the processing temperature of the selected resin, and the pressure is 10-15 MPa; In step 4, the heat carrier oil is also called heat transfer oil, and the heat transfer oil is selected from alkyl biphenyl type heat transfer oil; The sealing material for the exported liquid is fluororubber; in summer, when the ambient temperature is high, heat carrier oil is added; in winter, when the ambient temperature is low, the heat transfer oil is exported.

5. A composite material for a new energy vehicle battery box, characterized in that: The composite material is prepared by the method according to any one of claims 1 to 4.

6. A composite material molded product for a new energy vehicle battery box, characterized in that: The composite material molded product for new energy vehicle battery cases is applied to new energy vehicle battery cases within a wide temperature range. The composite material molded product for new energy vehicle battery cases includes the composite material for new energy vehicle battery cases according to claim 5. The composite material for new energy vehicle battery cases is prepared by the method described in any one of claims 1 to 4.

7. A new energy vehicle battery box, characterized in that: The new energy vehicle battery case includes the composite material molded product for the new energy vehicle battery case as claimed in claim 6.

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